1. Field of the Invention
This invention relates to amplifier beam type transducers, and more particularly, to an improved form of beam type transducer characterized in part by a suspension mechanism which maintains the beam in proper position on the support edge of an adjustable fulcrum, for pivotal movement thereabout with minimal hysteretic drag, while at the same time restraining the beam against all other movement and permitting the fulcrum to be adjusted laterally along the underside of the beam for varying the beam length on opposite sides of the support edge. 2. Description of the Prior Art
The amplifier beam type transducer of the present invention is in many respects similar to the transducer disclosed in my prior U.S. Pat. No. 3,772, 490, granted Nov. 13, 1973. This patent, and the prior art that was cited and considered by the Patent Office and listed on the front page of such patent should be consulted for the purpose of background information and putting the instant invention into proper perspective.
A disadvantage of the transducer disclosed in my aforementioned U.S. Pat. No. 3,772,490 is that the actuator arm positioned on the support edge of the notched fulcrum is subject to hysteresis, causing drag, particularly when small changes in actuating pressures are exerted on the input end of the beam by the input load cell. This condition results, in part at least, from the arrangement of the beam within the transducer housing. The beam is free to move laterally with respect to the longitudinal axis of the housing and sometimes does until making contact with either the front or rear side wall of such housing. The drag resulting from such contact inhibits the free pivotal movement of the beam in response to an input load and sometimes causes, particularly at low input pressure changes, the output signal variations to slightly lag input pressure deviations.
Another disadvantage of the transducer disclosed by my aforementioned U.S. Pat. No. 3,772,490 is that the finite incremental stepped positioning of the fulcrum lengthwise in the housing provides a limited range of output variations. Movement of the notched fulcrum between adjacent notches on the fulcrum support changes the actuating ratio a specific amount, e.g. a 5 lb. per square inch interval in a pressure gauge installation. Another disadvantage of my previous transducer is that the side wall of the housing has to be removed to change the position of the fulcrum; hence, a few moments of time must be spent removing the screws holding the side wall against the housing.
Screw type mechanisms for adjusting the position of the fulcrum supporting the beam of an amplifier type transducer are broadly old, as illustrated, for example, by the following: U.S. Pat. No. 2,304,783, granted Dec. 15, 1942, to Robert R. Donaldson; U.S. Pat. No. 2,548,807, granted Apr. 10, 1951 to Miles Morgan et al; and U.S. Pat. No. 2,740,295, granted Apr. 3, 1956 to Eugene Perchonok.